Method and system for signal generation via a temperature sensing crystal integrated circuit

ABSTRACT

Disclosed are various embodiments involving correction of signals generated by a crystal oscillator. An age of an integrated circuit or a time of use of the integrated circuit may be determined. A signal generated from a crystal of the integrated circuit may be modified based at least in part on the determined age of the integrated circuit or the determined time of use of the integrated circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application is a continuation of U.S. patent applicationSer. No. 13/237,823 filed on Sep. 20, 2011, which is a continuation ofU.S. patent application Ser. No. 12/364,046 filed on Feb. 2, 2009,which, in turn, claimed priority to U.S. Provisional Patent ApplicationSer. No. 61/025,724 filed on Feb. 1, 2008, and U.S. Provisional PatentApplication Ser. No. 61/088,893 filed on Aug. 14, 2008.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to signal processing. Morespecifically, certain embodiments of the invention relate to a methodand system for signal generation via a temperature sensing crystalintegrated circuit.

BACKGROUND OF THE INVENTION

A crystal oscillator is an electronic circuit that uses mechanicalresonance of a vibrating crystal of piezoelectric material to create anelectrical signal with a relatively precise frequency. This frequency iscommonly used as a reference or clock signal for a variety of circuits.The vibration of the crystal may vary with temperature and/or over time.Such variations in the resonant frequency of the crystal may createinstabilities or lead to other problems in an electronic system.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for signal generation via atemperature sensing crystal integrated circuit, substantially as shownin and/or described in connection with at least one of the figures, asset forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary communication devicecomprising a temperature sensing crystal integrated circuit (TSCIC), inaccordance with an embodiment of the invention.

FIG. 2A is a block diagram illustrating an exemplary TSCIC, inaccordance with an embodiment of the invention.

FIG. 2B is a block diagram illustrating another exemplary TSCIC, inaccordance with an embodiment of the invention.

FIG. 3A illustrates exemplary registers of the TSCIC, in accordance withan embodiment of the invention.

FIG. 3B illustrates exemplary data tables stored in a TSCIC, inaccordance with an embodiment of the invention.

FIG. 4 is a diagram illustrating a communication device comprising aTSCIC operable to download data for the TSCIC over a network, inaccordance with an embodiment of the invention.

FIG. 5A is a flow chart illustrating exemplary steps for operation of asystem comprising a TSCIC, in accordance with an embodiment of theinvention.

FIG. 5B is a diagram illustrating exemplary steps for updating TSCICdata, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor signal generation via a temperature sensing crystal integratedcircuit. In various embodiments of the invention, a temperature sensingcrystal integrated circuit (TSCIC) comprising a memory and a crystal orcrystal oscillator may be operable to generate a signal indicative of ameasured temperature within the TSCIC. The generated signal and datastored in the memory may be utilized to configure one or more circuitscommunicatively coupled to the TSCIC. The data stored in the memory maycharacterize behavior of the TSCIC as a function of temperature and/ortime. The data characterizing the behavior of the TSCIC may indicatevariations in frequency of the crystal or crystal oscillator as afunction of temperature and/or time. The data characterizing thebehavior of the TSCIC may comprise one or both of a frequency value anda frequency correction value. The data characterizing the behavior ofthe TSCIC may be copied from the memory integrated within the TSCIC to amemory that is external to the TSCIC. Changes in operation of the TSCICover time may also be determined. The determined changes may be utilizedto update at least a portion of the data stored in the memory integratedwith the TSCIC. The data stored in the memory integrated within theTSCIC may comprise data points of a frequency versus temperatureindication curve of the TSCIC. The data stored in the memory integratedwithin the TSCIC may comprise polynomial coefficients of a splineinterpolation of data points of a frequency versus temperatureindication curve of the TSCIC. The data stored in the memory integratedwithin the TSCIC may comprise a unique identifier of the TSCIC.

FIG. 1 illustrates an exemplary communication device comprising atemperature sensing crystal integrated circuit (TSCIC), in accordancewith an embodiment of the invention. Although a communication device isused for illustration, a TSCIC may be utilized in any type of electronicdevice. In one exemplary embodiment of the invention, the TSCIC may beutilized in a GPS system to enable fast(er) acquisition of GPS signals.The communication device 102 may comprise an antenna 152, a transmitterand/or receiver module (Tx/Rx) 154, a processor 160, a memory 162, ananalog to digital converter (ADC) 164, a TSCIC 158, a display 106, usercontrols 108, a speaker 104, and a microphone 110.

The antenna 152 may be suitable for transmitting and/or receivingwireless signals. Although a single antenna is illustrated, theinvention is not so limited. In this regard, the Tx/Rx 154 may utilize acommon antenna for transmission and reception, may utilize differentantennas for transmission and reception, and/or may utilize a pluralityof antennas for transmission and/or reception.

The temperature sensing crystal integrated circuit (TSCIC) 158 maycomprise a crystal and suitable logic, circuitry, and/or code that maybe operable to generate one or more oscillating signals. Additionally,the TSCIC 158 may provide one or more signals and data that may enabledetermination of a frequency of the generated oscillating signals overtime and/or temperature variations. Block diagrams of exemplary TSCICsare described below with respect to FIGS. 2A and 2B. In some embodimentsof the invention, the TSCIC 158 may be coupled to one or more externalcomponents to realize a crystal oscillator circuit. In other embodimentsof the invention, the TSCIC 158 may comprise one or more active and/orpassive components coupled to a crystal to realize a crystal oscillatorcircuit. In such embodiments, the TSCIC 158 may generate an oscillatingsignal without external components.

The frequency synthesizer 156 may comprise suitable logic, circuitry,and/or code that may be operable to generate one or more oscillatingsignals. In some embodiments of the invention, the frequency synthesizer156 may comprise active and/or passive components which may be coupledto xtal+ and xtal− terminals of the TSCIC 158 to realize a crystaloscillator circuit. In some embodiments of the invention, the frequencysynthesizer may comprise, for example, an integer-N PLL, fractional-NPLL, and/or a direct digital frequency synthesizer (DDFS). An output ofthe crystal oscillator circuit may be coupled to and provide a referencefrequency to the PLL and/or DDFS.

In the exemplary embodiment of the invention depicted in FIG. 1, thefrequency synthesizer 156 is shown as a separate block, however, theinvention is not so limited. In various embodiments of the invention aportion, or all, of the frequency synthesizer 156 may be integrated intothe TSCIC 158 and/or a portion, or all, of the frequency synthesizer 156may be integrated into the Tx/Rx 154.

The Tx/Rx 154 may comprise suitable logic, circuitry, interfaces, and/orcode that may be operable to transmit and/or receive signals utilizing avariety of wireless protocols. Exemplary communication wirelessprotocols utilized by the communication device 102 may comprise variouscellular protocols, WiMAX, Bluetooth, Wi-Fi, DVB-H/S/T, GNSS, broadcastradio, and broadcast television. The Tx/Rx 154 may be operable toperform amplification, down-conversion, filtering, demodulation, andanalog to digital conversion of received signals. The Tx/Rx 154 may beoperable to perform amplification, up-conversion, filtering, modulation,and digital to analog conversion of signals to be transmitted. Invarious embodiments of the invention, the Tx/Rx 154 may utilize one ormore reference frequencies from the frequency synthesizer 156 and/or theTSCIC 158.

The processor 160 may comprise suitable logic, circuitry, interfaces,and/or code that may enable processing data and/or controllingoperations of the communication device 102. The processor 160 may beenabled to provide and receive control signals to and from the variousother portions of the communication device 102. The processor 160 maycontrol transfers of data between various portions of the communicationdevice 102. In this regard, the processor 160 may control reads andwrites to memories and/or control registers in the communication device102. Additionally, the processor 160 may enable execution ofapplications programs and/or code. The applications, programs, and/orcode may enable, for example, processing of data, configuring portionsof the communication device 102, and/or controlling operation of thecommunication device 102. For example, the processor 160 may comprise aplurality of registers and an arithmetic and logic unit (ALU) forperforming mathematic and logical manipulations of data and/or controlsignals.

The memory 162 may comprise suitable logic, circuitry, and/or code thatmay be operable to store information comprising parameters and/or codethat may effectuate the operation of the communication device 102.Stored information may comprise received data and/or data to bepresented, transmitted, and/or otherwise processed. For example, one ormore received portions of one or more datastreams may be buffered in thememory 162. The parameters may comprise configuration data and the codemay comprise operational code such as software and/or firmware, but theinformation need not be limited in this regard. In various embodimentsof the invention, the memory 162 may store data characterizing behaviorof the TSCIC 158.

The ADC 164 may comprise suitable logic, circuitry, interfaces and/orcode that may be operable to convert analog signals to a digitalrepresentation. In this regard, the ADC 164 may, for example, sample andquantize an analog signal at times specified by a sample clock. Invarious embodiments of the invention, the ADC 164 may generate digitalsignals of one or more serial or parallel bits.

The display 106 may comprise suitable logic, circuitry, interfacesand/or code that may be operable to provide visual information to,and/or enable interaction by, a user of the communication device 102. Invarious embodiments of the invention, a graphical user interface may bepresented via the display 106. The user interface of the mobilecommunication device 102 may be utilized to select which source orsources it may have a desire to receive content from. A frequency and/orwireless standard to be utilized for communication may be selected basedon user input. Accordingly, based on such user input, the frequencysynthesizer 156 and/or the Tx/Rx 154 may be adjusted and/or configured.In various embodiments of the invention, a visual media content such asvideo, images, and text may be presented via the display 106.

The user controls 108 may be operable to enable user interaction withthe communication device 102 to control services and/or content handledby the communication device 102. The user controls 108 may comprise, forexample, a keypad, a keyboard, a roller ball, a multidirectional button,a scroll wheels, and/or a touch screen.

The speaker 104 may be operable to present audio information to a user.The speaker may present voice from a phone call and/or music orringtones played back by the communication device.

The microphone 110 may be operable to convert acoustic signals intoelectronic signals. The microphone may enable a user to participate in aphone call and/or interact with the communication device via oral input.

In operation, various functions and/or portions of the communicationdevice 102 may utilize a reference frequency generated by the TSCIC 158and the frequency synthesizer 156. However, the reference frequency maychange with, for example, time and/or temperature. There may also behysteresis associated with temperature indications and/or frequencychanges in the TSCIC 158. Accordingly, during production of the TSCIC158, data characterizing the behavior of the TSCIC 158 may be stored inthe TSCIC 158. In some embodiments of the invention, the data may comefrom characterization and/or measurement of the TSCIC 158 itself. Inother embodiments of the invention, the data may come fromcharacterization of one or more other TSCICs, such as a TSCIC from asame production run or lot, which may be representative of behavior ofthe TSCIC 158.

The characterization data may be utilized to configure and/or controlportions of the communication system 102 to compensate for variations inthe behavior of the TSCIC 158 over time and/or temperature. In variousembodiments of the invention, during operation of the communicationdevice 102, the processor 160 may copy characterization data from theTSCIC 158 to the memory 162. Subsequently, the processor 160 may receivea temperature indication, which may be an analog voltage or digitalrepresentation of a voltage, from the TSCIC 158 and generate one or morecontrol signals to configure the Tx/Rx 154 and/or the frequencysynthesizer 156 based on the copied data and the received temperatureindication. For example, the processor 160 may configure a frequencydivider of a PLL in the frequency synthesizer 156. In other embodimentsof the invention, the processor 160 may not copy the data to memory 162but may read the data from the TSCIC 158 as needed. In some embodimentsof the invention, the processor 160 may read an identifier from theTSCIC 158 and/or the memory 162 and utilize that identifier to downloadcharacterization data via a network.

In an exemplary embodiment of the invention, the communication device102 may be operable to determine location information based on receivedglobal navigation satellite system (e.g., GPS, GLONASS, or GALILEO)signals. The TSCIC 158 may generate a temperature indication and theprocessor 160 may adjust a frequency output by the frequency synthesizer156 to the Tx/Rx 154, where the frequency may be utilized for receivingGNSS signals. Additionally, the processor 160 may estimate theuncertainty or error in the adjusted frequency of the PLL. In thisregard, the accuracy of the estimate may determine an effort or timerequired for the Tx/Rx 154 to lock onto the GPS signals and determinethe location of the device 102. In various embodiments of the invention,the frequency accuracy may be estimated based on or more of thefollowing factors: time since the last frequency adjustment, the rate ofchange of temperature of the TSCIC 158 (or a crystal therein), timesince start up of a crystal oscillator, past frequency estimatescorresponding to the current temperature indication, past frequencyestimates corresponding to other temperature indications, pasttemperature indications, and hysteresis of a crystal oscillator.

FIG. 2A is a block diagram illustrating an exemplary TSCIC, inaccordance with an embodiment of the invention. Referring to FIG. 2A,there is shown TSCIC 158 a and exemplary coupling between the variousdevices of the communication device 102. The TSCIC 158 a may be anexemplary embodiment of the TSCIC 158 of FIG. 1. In an exemplaryembodiment of the invention, the frequency synthesizer 156, theprocessor 160, the memory 162, and the ADC 164 may be integrated into asystem on chip (SoC). The TSCIC 158 a comprises a crystal 206, atemperature sensing module 212, and a memory 216. Additionally, in someembodiments of the invention, the TSCIC 158 a may comprise a powerconditioning block 204.

The frequency synthesizer 156, the processor 160, the memory 162, theADC 164, and the Tx/Rx 154 may be as described with respect to FIG. 1.

The power conditioning block 204 may comprise suitable logic, circuitry,interfaces, and/or code that may be operable to generate one or moreregulated voltages and/or currents from a supply voltage Vdd−Vss. Invarious embodiments of the invention, the power conditioning block 204may be operable to implement a power-on-reset to ensure the TSCIC 158 apowers up and/or initializes properly. In an exemplary embodiment of theinvention, the voltage Vdd may be +1.8V and Vss may be 0V or GND. Thepower conditioning block 204 may be operable to reduce, increase, limit,filter, or otherwise condition the supply voltage to generate powerrails for powering the temperature sensing module 212 and the memory216. Notwithstanding, in various embodiments of the invention the TSCIC158 a may function reliably and/or sufficiently from an external powersupply and may not comprise a power conditioning block 204.

The crystal 206 may comprise piezoelectric material. A resonantfrequency of the crystal 206 may be utilized to provide a referencefrequency for an electronic circuit. The resonant frequency of thecrystal 206 may depend on the material, the size, and the shape of thematerial, and may also depend on the temperature of the crystal.Accordingly, aspects of the invention may be operable to providecompensation for the temperature dependence of the resonant frequency ofthe crystal 206. Devices external to the TSCIC 158 a may be coupled tothe crystal 206 via the terminals 208 and 210. In this regard, one ormore devices such as other processors or frequency synthesizers,represented generically as device 221, may be coupled to the terminals208 and 210 instead of, or in addition to, the frequency synthesizer156.

The memory 216 may comprise suitable logic, circuitry, interfaces,and/or code operable to store data. The memory 216 may be nonvolatilememory such as flash or fuse based memory or an EEPROM. The memory 216may be read-only or may be writable. Accordingly, data, which may becompressed utilizing known or proprietary algorithms, may be stored inthe memory 216 during production of the TSCIC 158 a and may be remainvalid during and subsequent to installation of the TSCIC 158 a into adevice such as the communication device 102 of FIG. 1. One or more flagsin the memory 216 may indicate whether the memory 216 is writable and/orwhether contents of the memory 216 have been modified. Data and/orcontrol signals may be communicated between the memory 216 and theprocessor 160 via the terminal 218. Additionally, one or more devicessuch as other processors and/or controllers, represented generically asdevice 223, may be coupled to the terminal 218 instead of, or inaddition to, the processor 160.

The temperature sensing module 212 may comprise suitable logic,circuitry, interfaces, and/or code that may be operable to generate asignal 213 which may be indicative of a temperature of the crystal 206or a calibration voltage. Temperature indications and calibrationvoltages may be communicated to devices external to the TSCIC 158 a viathe terminal 214. Additionally, one or more devices, such as otherprocessors and/or analog-to-digital converters, represented genericallyas device 227, may be coupled to the terminal 214 instead of, or inaddition to, the ADC 164. Whether signal 213 corresponds to atemperature or calibration voltage may depend, for example, on one ormore control signals or a state of the temperature sensing module. In anexemplary embodiment of the invention, the signal 213 may be a voltageranging from 0V to 1V over a temperature range of −30° C. to +75° C.,with 0V and/or 1V being output as calibration voltages. Notwithstanding,the invention is not so limited and other voltage ranges and/ortemperature ranges may be utilized without departing from the variousembodiments of the invention.

In operation, the power conditioning module 204 may be operable tosupply a conditioned and/or regulated voltage and/or current to thetemperature sensing module 202 and the memory 216. The temperaturesensing module 212 may output a temperature indication via the terminal214 and the ADC 164 may digitize the temperature indication to generatea digitized signal 225. The memory 216 may execute read and/or writecommands received from the processor 160 via the terminal 218. In thismanner, data and/or parameters may be stored and/or retrieved from thememory 216. The frequency synthesizer 156 may generate a referencefrequency by applying a voltage across the xtal+ and xtal− terminalsthereby causing the crystal 206 to vibrate at or near its resonantfrequency. The reference frequency may be conveyed to one or morecomponents of the system 200.

In some embodiments of the invention, the processor 160 may, uponstart-up, copy data from the memory 216 to the memory 162. In thisregard, copying data from the memory 216 to the memory 162 may be partof the processor's boot procedure or function, for example.

After power up, or a reset, and initialization of the various devices ofthe communication device 102, the processor 160 may, via the ADC 164,receive a digitized temperature indication from the TSCIC 158 a. Theprocessor 160 may then reference characterization data in either thememory 162, if the data was copied there from the memory 216, or in thememory 216, to determine the frequency of the crystal 206 and/ordetermine a frequency correction factor corresponding to the receivedtemperature indication. In this regard, values stored in the memory 162may comprise frequencies values or frequency correction values, where afrequency correction value may be, for example, a deviation from anominal or center frequency of the crystal at a reference temperatureindication. The processor 160 may then adjust the frequency synthesizer156 based on the determined frequency and/or frequency correctionfactor. In various embodiments of the invention, the processor 160 mayperiodically check the digitized temperature indication and adjust thefrequency synthesizer 156 and/or the Tx/Rx 154 as necessary.

In some embodiments of the invention, data stored in the memory 216, andin some instances copied to the memory 162, may comprise datacharacterizing the behavior of the crystal 206 as a function of time.For example, the data may indicate jitter or frequency drift as afunction of time from start-up of the crystal 206, time from manufactureof the crystal 206, and/or total time of operation of the crystal 206.Accordingly, the processor 160 may periodically check the data andadjust the frequency synthesizer 156 and/or the Tx/Rx 154 as necessarybased on one or more time parameters.

In some embodiments of the invention, the memory 162 may be volatile andupon power up of the communication device 102, the processor 160 mayread data from the memory 216 to determine initial frequencies and/orother parameters of the communication device 102. For example, theprocessor 160 may read data to configure a frequency of operation of thecommunication bus 274.

FIG. 2B is a block diagram illustrating another exemplary TSCIC, inaccordance with an embodiment of the invention. Referring to FIG. 2B,there is shown TSCIC 158 b and exemplary coupling between the variousdevices of the communication device 102. The TSCIC 158 b may be anexemplary embodiment of the TSCIC 158 of FIG. 1. The TSCIC 158 bcomprises band gap reference module 256, regulator 264, crystaloscillator 254, switching element 266, buffer 268, temperature sensingmodule 212, memory 216, and communication and control module 272.

The communication and control module 272 may comprise suitable logic,circuitry, interfaces, and/or code operable to communicate with externaldevices via the communication bus 274 and to control and/or configurethe various components of the TSCIC 158 b. The communication and controlmodule 272 may comprise one or more registers for configuring the TSCIC158 b and/or indicating attributes of the TSCIC 158 b. The communicationand control module 272 may be operable to receive one or more signalsfrom the various other components of the TSCIC 158 b. The communicationand control module 272 may be operable to receive signals via thecommunication bus 274. The communication and control module 272 may beoperable to generate one or more signals to control or configure othercomponents of the TSCIC 158 b. In this regard, control signals may begenerated in response to signals received from the other components ofthe TSCIC 158 b and/or via the communication bus 274.

The communication and control module 272 may be operable to transmitsignals to other devices via the communication bus 274. In this regard,control signals generated may be in response to signals received fromthe other components of the TSCIC 158 b and/or via the bus 274. Forexample, the communication and control module 272 may be operable towrite and/or read to and/or from the memory 216 based on commandsreceived via the communication bus 274. In this regard, thecommunication and control module 272 may write data received via the bus274 to the memory 216 and may communicate data read from the memory 216over the communication bus 274.

The frequency synthesizer 156, the processor 160, the memory 162, theADC 164, and the Tx/Rx 154 may be as described with respect to FIG. 1.The temperature sensing module 212 and the memory 216 may besubstantially as described with respect to FIG. 2A.

The band gap reference module 256 may be operable to output a referencevoltage that may be approximately equal to the theoretical band gap ofthe material of which the TSCIC 158 b is fabricated. For example, forsilicon the band gap reference voltage 257 may be approximately 1.25V.The band gap reference 257 may be provided to the temperature sensingmodule 212 such that the signal 213 generated by the temperature sensingmodule 212 may be highly accurate and stable over a range oftemperatures and over time. In one exemplary embodiment of theinvention, the band gap reference module 256 may be a sub-module of thepower conditioning module 204 described with respect to FIG. 2A.

The regulator 264 may comprise suitable logic, circuitry, interfaces,and/or code that may be operable to regulate one or more voltages and/orcurrents supplied to the crystal oscillator 254, the temperature sensingmodule 212, the memory 216, the switching element 266, the buffer 268,and/or the communication and control module 272. In this regard, theregulator 264 be a linear or switching regulator and may filter, boost,buck, enable and disable, or otherwise condition the power in the TSCIC158 b. In one exemplary embodiment of the invention, the regulator 264may be a sub-module of the power conditioning module 204 described withrespect to FIG. 2A.

The crystal oscillator 254 may comprise an oscillator circuit 258coupled to the crystal 206 and buffered by the buffer 260. The crystal206 may be coupled as a load of the oscillator circuit 258 which maycomprise one or more active and/or passive components.

The switching element 266 may comprise suitable logic, circuitry,interfaces, and/or code operable to route either the band gap reference257 or the signal 213 to the buffer 268 for conveyance to the ADC 164via the terminal 214. The switching element 266 may be controlled viaone or more signals from the communication and control module 272. In anexemplary embodiment of the invention, the switching element 266 maycomprise a multiplexer.

In operation, the communication and control module 272 may receive acommand to output a temperature indication via the terminal 214.Accordingly, the temperature sensing module 212 may be configured suchthat the signal 213 indicates a temperature. The switching element 266may be configured to route the signal 213 to the terminal 214.Accordingly, the ADC 164 may digitize the signal 213 to generate thedigital signal 225. The processor 160 may receive the digital signal 225and reference either the memory 162 or the memory 216 to determine thefrequency and/or a frequency correction value, corresponding to thereceived temperature indication, for the crystal oscillator 254. Theprocessor 160 may then reconfigure, and/or adjust one or more controlsignals to, the frequency synthesizer 156 and/or the Tx/Rx 158 b basedon the determined frequency and/or frequency correction value.

Upon power up, the crystal oscillator 254 may begin generating anoscillating signal F_(ref). The frequency synthesizer 156 may receivethe oscillating signal F_(ref) via the terminal 262. In some embodimentsof the invention, F_(ref) may be a reference frequency for one or morePLLs within the frequency synthesizer 156. In this regard, the one ormore PLLs may generate one or more signals having an integer orfractional multiple of F_(ref). In some embodiments of the invention, aDDFS in the frequency synthesizer 156 may be clocked by F_(ref) togenerate one or more signals. In some embodiments of the invention,F_(ref) may be divided down by the frequency divider to generate one ormore signals that are lower in frequency.

In some embodiments of the invention, upon start-up of the processor 160and/or the communication and control module 272, data may be copied fromthe memory 216 to the memory 162 via the communication bus 274. In thisregard, copying data from the memory 216 to the memory 162 may be partof the processor's boot code and/or an initial state of thecommunication and control module 272, for example.

FIG. 3A illustrates exemplary registers of the TSCIC, in accordance withan embodiment of the invention. Referring to FIG. 3A there is shown anexemplary register map 300 for the TSCIC 158. The exemplary registerscomprise CMD_REG 302, DATA_SIZE 304, CHIP_ID 306, CRC 308, CNTR_FREQ310, and MFR_DATE 312. In an exemplary embodiment of the invention, theregisters may be implemented in the communication and control module272. In various embodiments of the invention, the contents of theregisters may also be stored in the memory 216.

The register CMD_REG 302 may be utilized to issue a command to orinstruct the TSCIC 158 to execute various operations. Exemplaryoperations may comprise a command to execute soft reset of the TSCIC158, a command to output a calibration voltage via the terminal 214, acommand to output a temperature indication, and one or more commands todisable one or more portions of the TSCIC 158. Thus, CMD_REG 302 may bea writeable register utilized to control a configuration and/oroperation of the TSCIC 158. In regard to disabling portions of the TSCIC158, the TSCIC may support low power and/or “sleep” modes to reducepower consumption in the communication device 102.

The register DATA_SIZE 304 may comprise a value to indicate the size ofone or more data tables stored in the memory 216 and a cyclic redundancycheck (CRC) value to verify that the contents of the memory 216 have notbeen corrupted.

The register CHIP_ID 306 may comprise a value to indicate a version ofthe TSCIC 158. In this regard, the CHIP_ID 306 may indicatecapabilities, features, configuration, or other characteristics of theTSCIC 158. CHIP_ID may be utilized by external devices such as theprocessor 160 to determine compatibility with the TSCIC 158. In thisregard, TSCICs produced by different manufacturers may exhibit differentcharacteristics and/or features. In some embodiments of the invention,the value stored in CHIP_ID 306 may be utilized to access a database ofTSCIC data.

The register CTR_FREQ 310 may comprise a value that may indicate anerror in the center frequency. For the TSCIC 158 a of FIG. 2A, CTR_FREQ310 may indicate an error in center frequency of the crystal 206 fromthe nominal center frequency. For the TSCIC 158 b of FIG. 2B, CTR_FREQ310 may indicate an error in center frequency of the crystal oscillator254 from the nominal center frequency. The value stored in CTR_FREQ 310may be determined during production of the TSCIC 158.

The register CRC 308 may comprise a computed CRC of one or more datatables stored in the memory 216 and the register CTR_FREQ 310. In anexemplary embodiment of the invention, the contents of CTR_FREQ 310 maybe appended to the one or more data tables prior to calculating the CRC.

The register MFR_DATE 312 may indicate a date on which the TSCIC 158 wascharacterized and the data was stored in the memory 216. In someembodiments of the invention, the MFR_DATE 312 may be utilized to accessa database of TSCIC data. In this regard, MFR_DATE 312 may be utilizedin compensating for changes in behavior of a TSCIC over time.

In operation, a configuration of the TSCIC 158 may be based on thecontents of the registers. In an exemplary embodiment of the invention,commands to read the contents of the registers, and write to the CMD_REG302, may be received by the communication and control module 272 fromthe processor 160. For reads, the communication and control module 272may respond by communicating the register contents over the bus 274. Forwrites to the CMD_REG 302, the communication and control module 272 mayupdate the register and one or more portions of the TSCIC 158 may beconfigured as a result of the new CMD_REG 302 value.

FIG. 3B illustrates exemplary data tables stored in a TSCIC, inaccordance with an embodiment of the invention. Referring to FIG. 3Bthere are shown exemplary data tables 320, 330, and 340. In variousembodiments of the invention, one or more of the data tables may bestored in the memory 216. In various embodiments of the invention, thedata tables, or one or more fields of the data tables 320, 330, and 340may be compressed.

The data table 320 may comprise entries 321 ₁, . . . , 321 _(M)corresponding to M data points of a temperature indication versusfrequency curve characterizing the TSCIC 158, where M is an integer. Thefields 322 ₁, . . . , 322 _(M) may comprise M measured temperatureindications. The fields 324 ₁, . . . , 324 _(M) may comprise M measuredfrequencies, or measured frequency correction values, corresponding,respectively, to the M measured temperature indications. The fields 326₁, . . . , 326 _(M) may comprise M measured values of a 1^(st)calibration voltage corresponding, respectively, to the M measuredtemperature indications. The fields 328 ₁, . . . , 328 _(M) may compriseM measured values of a 2^(nd) calibration voltage corresponding,respectively, to the M measured temperature indications.

In operation, in an exemplary embodiment of the invention, the processor160 may search for a temperature indications, V_(X), in the fields 322₁, . . . , 322 _(M). In some instances V_(X) may be found in a field 322_(m), where m is between 1 and M. Accordingly, the processor 160 mayread the fields 324 _(m) 326 _(m) and 328 _(m) to configure the Tx/Rx154 and/or the frequency synthesizer 156. In some instances a match forV_(X) may not be found in the fields 322 ₁, . . . , 322 _(M). In someembodiments of the invention, the processor 160 may round Vx up or downto the closest entry 322 _(m) and the corresponding fields 324 _(m) 326_(m) and 328 _(m) may be utilized for configuring the system. In otherembodiments of the invention, the processor may round up and down todetermine the two nearest fields 322 _(m) and 322 _(m+1). The processormay then interpolate between the value of field 324 _(m) and the valueof field 324 _(m+1) to calculate a frequency and/or frequency correctionvalue.

The data table 330 may comprise entries 331 ₁, . . . , 331 _(P)corresponding to P data points of a time versus frequency curve of theTSCIC 158, where P is an integer. In an exemplary embodiment of theinvention, the fields 332 ₁, . . . , 332 _(P), may each comprise a valuecorresponding to a time since start-up of the TSCIC 158. In anotherexemplary embodiment of the invention, the fields 334 ₁, . . . , 334_(P), may each comprise a frequency or frequency adjustment valuecorresponding to a total time of operation of the crystal 206 or crystaloscillator 254.

In operation, the processor 160, utilizing the memory 162, may keeptrack of how long the crystal 206 or crystal oscillator 254 has beenoperating, either since its last start-up or over its lifetime.Accordingly, when the time of operation reaches or exceeds the value ofentry 332 _(p), the processor 160 may utilize the frequency or frequencyadjustment value stored in entry 334 _(p) to configure or adjust thecommunication device 102, where p is between 1 and P.

The data table 340 may comprise entries 341 ₁, . . . , 341 _(M)corresponding to M−1 pieces of a spline interpolation of M data pointsof a temperature indication versus frequency curve characterizing theTSCIC 158, where M is an integer. In this regard, the fields 342 ₁, . .. , 342 _(M) may each comprise two measured temperature indicationsserving as endpoints of a piece of the spline. The fields 344 ₁, . . . ,344 _(M-1), 346 ₁, . . . , 346 _(M-1) 348 ₁, . . . , 348 _(M-1); 350 ₁,. . . , 350 _(M-1) may comprise coefficients of M−1 polynomialsapproximating the M−1 pieces of the spline. The fields 352 ₁, . . . ,352 _(M-1) may comprise M−1 measured values of a 1^(st) calibrationvoltage corresponding, respectively, to the M−1 pieces of the spline.The fields 354 ₁, . . . , 354 _(M-1) may M−1 measured values of a 2^(nd)calibration voltage corresponding, respectively, to the M−1 pieces ofthe spline. In this regard, in an exemplary embodiment of the invention,the calibration voltages may be relatively constant and thus may betreated as constant over each piece of the spline.

In operation, in an exemplary embodiment of the invention, the processor160 may search for a range encompassing a temperature indication, V_(X),in the fields 342 ₁, . . . 342 _(M-1). Upon finding the correcttemperature indication range in the field 342 _(m), where m is between 1and M−1, the processor 160 may read the polynomial coefficients fields344 _(m) 346 _(m), 348 _(m), and 350 _(m) and calculate a frequency orfrequency correction value utilizing the polynomial. In an exemplaryembodiment of the invention, the spline interpolation may be a cubicspline interpolation and thus each entry 341 may comprise fourcoefficients. However, the invention is not limited in the interpolationmethod used, and other types of interpolation may be utilized withoutdeparting from the spirit and/or scope of the various embodiments of theinvention.

FIG. 4 is a diagram illustrating a communication device comprising aTSCIC operable to upload and/or download data for the TSCIC over anetwork, in accordance with an embodiment of the invention. Referring toFIG. 4 there is shown the communication device 102 comprising the TSCIC158 communicatively coupled to a server 404 via a network 402.

The communication device 102 may be communicatively coupled to thenetwork 402 via a wired, optical, and/or wireless link. The network 402may utilize one or more wired, wireless, and/or optical protocols suchas Ethernet, ATM, T1/E1, T3/E3, Cellular, WiMAX, Wi-Fi, Bluetooth, PON,and SONET.

The server 404 may comprise suitable logic, circuitry, and/or code thatmay be operable to store information characterizing TSCICs and totransmit and receive such information over the network 402. Exemplaryinformation characterizing TSCICs may comprise estimated frequencyversus temperature indication data, actual frequency versus temperatureindication data, estimated frequency versus time data, and actualfrequency versus time data. Exemplary information stored on the server404 may comprise code, parameters, coefficients, and/or otherinformation for implementing one or more algorithms to determinebehavior of a TSCIC over temperature and/or time. Information stored onthe server 404 may comprise data uploaded by a manufacturer, such asdata measured during production and/or in test labs. Information storedon the server 404 may comprise and/or be based on information uploadedvia the network 402 from devices in use such as the communication device102.

In operation, the communication device 102 may communicate an identifierof the TSCIC 158 to the server 404 and the server 404 may respond bycommunicating data characterizing the TSCIC 158 to the communicationdevice 102. In an exemplary embodiment of the invention, a user of thecommunication device 102 may utilize a web-based database interface tolocate characterization data for the TSCIC 158. In various embodimentsof the invention, the data from the server 404 may modify or replacedata stored in the TSCIC 158. In various exemplary embodiments of theinvention, updated data on the server 404 may comprise, for example,data from a characterization of a TSCIC similar to the TSCIC 158. Forexample, another TSCIC from the same production run as the TSCIC 158 maybe kept by the manufacturer and measured over time to characterize theaging of the TSCICs. In various exemplary embodiments of the invention,updated data on the server 404 may have been uploaded from thecommunication device 102 and/or other electronic devices comprising aTSCIC 158. For example, devices such as the communication device 102 mayperiodically upload determined frequency versus temperature indicationand/or frequency versus time information to the server 404. The server404 may utilize the uploaded data to modify algorithms or data tableswhich may be subsequently downloaded by the communication device 102and/or other electronic devices. Information downloaded from the server404 may be utilized by the communication device 102 to replace or modifythe original data stored in the TSCIC 158 at the time of its manufactureand/or to replace or modify algorithms and/or functions utilized todetermine behavior of a TSCIC over temperature and/or time.

In some embodiments of the invention, the communication device 102 mayreceive and/or measure frequency information based on signals receivedvia wireless, wired, and/or optical connections to the network 402. Forexample, the communication device 102 may establish a cellularcommunication channel with a cellular base station 406 and frequencyinformation associated with the cellular communications may be utilizedto determine the frequency of the TSCIC 158. Similarly, thecommunication device 102 may acquire a GPS signal from, for example, asatellite 408 and frequency information associated with the GPScommunications may be utilized to determine the frequency of the TSCIC158. Furthermore, in some embodiments of the invention, frequencyinformation determined and/or measured based on communications with thenetwork 402 may be utilized to determine an error between actualbehavior of the TSCIC 158 and behavior predicted or expected based oninformation stored in the memory 216. Such differences between actualand expected behavior, along with corresponding temperature indicationsmay be uploaded to the server 404.

FIG. 5A is a flow chart illustrating exemplary steps for operation of asystem comprising a TSCIC, in accordance with an embodiment of theinvention. For illustration, the exemplary steps are described withreference to FIG. 2A. Referring to FIG. 5, the exemplary steps beginwith step 502 when the TSCIC 158 a is powered up. The TSCIC 158 a may,for example, perform a power-on-reset such that the various componentsare initialized to a known and/or default state. In some embodiments ofthe invention, power up and initialization of the TSCIC 158 a maycomprise a copying of data from the memory 216 integrated within theTSCIC 158 a to the system memory 162. In this regard, the data mayenable characterization of the TSCIC 158 a as a function of temperatureand/or time. Subsequent to step 502, the exemplary steps may advance tostep 504.

In step 504, a temperature indication, representing temperature of, ornear, the crystal 206 may be generated by the TSCIC 158 a. Theindication may be a voltage or a current, may be digitized, and may beinput to a system processor 160. Subsequent to step 504, the exemplarysteps may advance to step 506.

In step 506, the processor 160 may determine a behavior of the TSCICbased on the temperature indication and based on the data copied fromthe TSCIC. For example, one or more algorithms may be utilized by theprocessor 160 to determine a resonant frequency of the crystal 206.Subsequent to step 506, the exemplary steps may advance to step 508.

In step 508 the communication device 102 may be configured based on thedetermined behavior of the TSCIC. For example the frequency synthesizer156 and/or the Tx/Rx 154 may be reconfigured to compensate forvariations over temperature and/or time of the frequency of the crystal206. Subsequent to step 508, the exemplary steps may return to step 504.In this regard, the rate at which the steps 504-508 are repeated may beconfigurable based, for example, on power consumption requirementsand/or based on the stability of the temperature of the crystal 206.

FIG. 5B is a diagram illustrating exemplary steps for updating TSCICdata, in accordance with an embodiment of the invention. Forillustration, the exemplary steps are described with reference to thesystem of FIG. 4. The exemplary steps may begin with step 520 when thecommunication device 102 requires and/or desires to obtain up-to-datedata and/or algorithms that characterize behavior of the TSCIC 158. Inthis regard, the communication device 102 may check for updated dataand/or algorithms periodically or a user of the communication device 102may provide input to cause the communication device 102 to check forupdated data and/or algorithms. Subsequent to step 520, the exemplarysteps may advance to step 522.

In step 522, the communication device 102 may communicate the CHIP_IDand/or MFR_DATE associated with the TSCIC 158 to the server 404 via thenetwork 402. The CHIP_ID and/or the MFR_DATE may be utilized to look upinformation in a database. Subsequent to step 522, the exemplary stepsmay advance to step 524.

In step 524, information corresponding to the CHIP_ID and/or MFR_DATEmay be downloaded from the server 404 to the communication device 102.The downloaded information may comprise, for example, actual and/orestimated frequency versus temperature indication data, actual and/orestimated frequency versus time data, and/or updated code, parameters,and/or coefficients for implementing one or more algorithms fordetermining frequency of a crystal within the TSCIC 158. The downloadedinformation, and/or data derived therefrom, may be stored to a systemmemory and/or to a memory integrated within the TSCIC 158. Subsequent tostep 524, the exemplary steps may advance to step 526.

In step 526, the system may upload data to the server. In this regard,the communication device 102 may upload previously stored data and/orupload data determined based on the information downloaded in step 524.Subsequent to step 526, the exemplary steps may advance to step 528 andthe communication device 102 and the TSCIC 158 may enter normaloperation, which may be similar to the steps described with respect toFIG. 5A.

Various embodiments of the invention may provide a method and system forsignal generation via a temperature sensing crystal integrated circuit.In an exemplary embodiment of the invention, a temperature sensingcrystal integrated circuit (TSCIC) 158 comprising a memory 216 and acrystal 206 or crystal oscillator 254, that may be operable to generatea signal 213 indicative of a measured temperature. The generated signal213 and data, such as data tables 320, 330, and 340, stored in thememory 216 may be utilized to configure one or more circuits, such asthe Tx/Rx 154 and Frequency synthesizer 156, communicatively coupled tothe TSCIC 158. Data, such as data tables 320, 330, and 340, stored inthe memory 216 may characterize behavior of the TSCIC 158 as a functionof temperature and/or time. The data characterizing the behavior of theTSCIC 158 may indicate variations in frequency of the crystal 206 orcrystal oscillator 254 as a function of temperature and/or time. Thedata characterizing the behavior of the TSCIC may comprise one or bothof a frequency value and a frequency correction value. The datacharacterizing the behavior of the TSCIC may be copied from the memory216 integrated within the TSCIC 158 to a memory 162 that is external tothe TSCIC 158. Changes in operation of the TSCIC 158 over time may bedetermined. The determined changes may be utilized to update at least aportion of the data stored in the memory 216 integrated with the TSCIC.Data, such as the data table 320, stored in the memory 216 integratedwithin the TSCIC 158 may comprise data points of a frequency versustemperature indication curve of the TSCIC 158. Data, such as the datatable 340, stored in the memory 216 integrated within the TSCIC 158 maycomprise polynomial coefficients of a spline interpolation of datapoints of a frequency versus temperature indication curve of the TSCIC158. Data stored in the memory integrated within the TSCIC may comprisea unique identifier of the TSCIC.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for signalgeneration via a temperature sensing crystal integrated circuit.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

Therefore, at least the following is claimed:
 1. A method comprising:determining at least one of: an age of an integrated circuit or a timeof use of the integrated circuit; and modifying a signal generated froma crystal of the integrated circuit based at least in part on at leastone of: the determined age of the integrated circuit or the determinedtime of use of the integrated circuit.
 2. The method of claim 1, whereinmodifying the signal is further based at least in part on dataindicating a frequency of the crystal as a function of time.
 3. Themethod of claim 1, wherein modifying the signal is further based atleast in part on a temperature signal generated by a temperature sensorof the integrated circuit.
 4. The method of claim 3, wherein modifyingthe signal is further based at least in part on data indicating afrequency of the crystal as a function of temperature.
 5. The method ofclaim 1, further comprising: downloading data from a network; andmodifying the signal further based at least in part on the downloadeddata.
 6. The method of claim 1, further comprising: read data stored ina memory of the integrated circuit; and send the data read from thememory to a network.
 7. The method of claim 1, further comprisingsending the modified signal to a network via a communication bus of theintegrated circuit.
 8. The method of claim 1, wherein the integratedcircuit stores an identifier, and determining at least one of: the ageof the integrated circuit or the time of use of the integrated circuitfurther comprises: requesting data from a network based at least in parton the identifier; and determining at least one of: the age of theintegrated circuit or the time of use of the integrated circuit based atleast in part on the requested data.
 9. The method of claim 8, whereinthe identifier corresponds to a date of manufacture for the integratedcircuit.
 10. A system, comprising: an integrated circuit comprising acrystal oscillator, the integrated circuit being configured to:determine at least one of: an age of an integrated circuit or a time ofuse of the integrated circuit; and correct an oscillating signalgenerated by the crystal oscillator based at least in part on at leastone of: the determined age of the integrated circuit or the determinedtime of use of the integrated circuit.
 11. The system of claim 10,wherein the integrated circuit further comprises a temperature sensor,and the integrated circuit is further configured to correct theoscillating signal based at least in part on an output of thetemperature sensor.
 12. The system of claim 11, wherein the integratedcircuit stores data indicating a frequency of the crystal as a functionof temperature, and the integrated circuit is further configured tocorrect the oscillating signal based at least in part on the data. 13.The system of claim 10, wherein the integrated circuit stores dataindicating a frequency of the crystal oscillator as a function of time,and the integrated circuit is further configured to correct theoscillating signal based at least in part on the data.
 14. The system ofclaim 13, wherein the integrated circuit is configured to obtain thedata indicating the frequency of the crystal oscillator as the functionof time via a network.
 15. The system of claim 10, wherein theintegrated circuit further comprises a memory and a communication bus,and the memory is writeable via the communication bus.
 16. The system ofclaim 10, wherein the time of use corresponds to how long the crystaloscillator has been oscillating since a most-recent start up.
 17. Thesystem of claim 10, wherein the time of use corresponds to how long thecrystal oscillator has been in use over its lifetime.
 18. A system,comprising: circuitry capable of: determining at least one of: an age ofa crystal oscillator circuit or a time of use of the crystal oscillatorcircuit; and modifying a signal generated by the crystal oscillatorcircuit based at least in part on at least one of: the determined age ofthe crystal oscillator circuit or the determined time of use of thecrystal oscillator circuit.
 19. The system of claim 18, wherein thecircuitry is further capable of: determining a temperature readingassociated with the crystal oscillator circuit; and modifying the signalbased at least in part on the temperature reading.
 20. The system ofclaim 18, wherein the circuitry is further capable of modifying thesignal based at least in part on a fixed value indicating an error in acenter frequency of the crystal oscillator circuit.